A LAN (Local Area Network) is the network on the customer side of a router. It connects devices on a single site, such as a building, cabinet, vehicle, or industrial enclosure. In an IoT deployment, the LAN typically connects cameras, sensors, controllers, IP phones, or computers to the cellular router that provides their WAN link to the internet.

In short: Industrial routers act as the gateway between the LAN and the WAN. They provide LAN connectivity via Ethernet ports (typically Gigabit), Wi-Fi (2.4 GHz, 5 GHz, and increasingly Wi-Fi 6), and sometimes specialist interfaces like RS-232, RS-485, or CAN bus for industrial equipment. LAN traffic stays local unless explicitly routed to the WAN.

The number and type of LAN ports drives router selection in many deployments. A Teltonika RUT241 with two Ethernet ports suits a single connected device with cellular failover. A RUT956 or RUTM52 with multiple LAN ports suits a small site with several connected devices. A TSW (Teltonika Switch) range extends LAN capacity further when a router's onboard port count is not enough.

LAN-side security is often overlooked. Devices on the LAN trust each other by default, so a compromised camera or controller can attack other devices on the same network. VLAN segmentation, firewall rules between zones, and isolated guest Wi-Fi all help limit lateral movement within the LAN.